Patent offices have financial incentives to approve applications
Patent offices are generally funded by charging a fee for patents. This encourages them to approve as many applications as possible by minimising exclusions. When "programs for computers" are excluded, that limits their sources of revenue, so it's predictable that they will look for ways to suppress such an exception.
European Patent Office
As described by the Staff Union of the EPO in a 2008 press release:
Since many of the national offices are financially dependent on the fees resulting from the work of the EPO, decisions taken by the EPO Administrative Council are influenced by the interests of the national patent offices and the desire for as many patents to be granted as possible, believes the SUEPO. Constant decisions in favour of quantity damage the quality of the patents, however.
€4.6 billion at stake
For the national patent offices, there is a lot of money at stake. In 2007, the annual fees for examined and granted patents totalled €600 million. 50% thereof, i.e. €300 million, remains with the national patent offices. The total amount accruing from the annual fees for granted patents alone over the next few years was already known at the start of 2008: €4.6 billion – half of which, €2.3 billion, would go to the national patent offices. For this reason, insists SUEPO, the probability is great that the members of the Administrative Council will manage the EPO predominantly with an eye to the interests of their own offices.
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